<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="jquery-3.3.1.min.js"></script>
</head>
<body>
<h2>表单过滤器</h2>
<h3>用户注册</h3>
<form action="">
    用户名：<input type="text" name="" id="" placeholder="请输入用户名"><br>
    用户密码：<input type="password" placeholder="请输入密码"><br>
    兴趣爱好：<input type="checkbox" name="hobby" value="python">
             <input type="checkbox" name="hobby" value="php">
             <input type="checkbox" name="hobby" value="java" checked>
             <input type="checkbox" name="hobby" value="html">
             <input type="checkbox" name="hobby" value="css" checked><br>
    <button type="submit">提交</button>
    <input type="text" disabled placeholder="禁用">
</form>
</body>
<script>
    $(function () {
        //  :  伪选择符
        $("input:text").css("border","1px solid red");
        $("input:password").attr("placeholder","至少8-20");
        $("input:checkbox").css("boxShadow","2px 2px 2px green");
        $("input:checked").css("boxShadow","2px 2px 2px red");

        //选择页面中的button/disable
        $(":button").css("backgroundColor","skyblue");
        $(":disabled").css("background","#ccc");


    })
</script>
</html>